Method and Apparatus for Producing Composite Structure

Abstract

The present invention relates to a method and apparatus for forming a composite structure, preferably for use in an absorbent structure used within the personal hygiene industry, such as for instance feminine hygiene garments, baby diapers and pants and adult incontinence garments. The present invention preferably provides a method and apparatus for depositing and positioning particulate materials in a desired pattern onto a moving carrier layer. The method allows accurate forming of a pattern of particulate material clusters at high production speed having improved attachment properties, with reduced raw material usage and relative low cost. The present invention foresees in the need for improved thin, flexible, lightweight absorbent structure having optimal absorption, distribution and retention.

What is claimed is: 
     
       1. A method for producing a composite structure comprising absorbent particulate material wherein the method comprises the steps of:
 providing an endless rotating drum incorporating a clustering means with perforations corresponding to a desired pattern; 
 driving the clustering means in a same direction as and in close proximity to a moving carrier layer; 
 feeding a pulsed particulate material stream from a particulate material supply means to the clustering means by creating pulses of particulate material; said pulsed particulate material stream comprising absorbent polymer material; 
 directing the pulsed particulate material stream through the perforations of the clustering means onto carrier deposit zones of the carrier layer; and 
 placing an auxiliary layer on top of the carrier layer on which particulate material has been deposited so as to form a sandwich structure. 
 
     
     
       2. The method of  claim 1 , wherein the method comprises immobilising, joining and/or restraining the particulate material to at least one of the carrier layer and auxiliary layer. 
     
     
       3. The method of  claim 1 , wherein at least one of the carrier layer and the auxiliary layer is made of a hydrophilic non-woven. 
     
     
       4. The method of  claim 1 , wherein at least one of the carrier layer and the auxiliary layer is made of a spunbonded, melt-blown, spunbonded (SMS) layer; or of a spunbonded, melt-blown, melt-blown, spunbonded (SMMS) structure. 
     
     
       5. The method of  claim 1 , wherein at least one of the carrier layer and the auxiliary layer is made of any one of the following materials: a nonwoven containing cellulosic fibers; a paper or tissue sheet; an airlaid, drylaid or wetlaid material. 
     
     
       6. The method of  claim 1 , wherein the pulsed particulate material stream comprises absorbent polymer material suspended in air. 
     
     
       7. The method of  claim 1 , wherein the step of directing the pulsed particulate material stream through the clustering means uses a feeding tube to deliver required amounts of particulate material into the clustering means. 
     
     
       8. The method of  claim 1 , wherein the absorbent polymer material has a mean particle size from about 10 μm to 1000 μm, said absorbent polymer material being selected to swell upon contact with liquids, such as bodily exudates. 
     
     
       9. The method of  claim 8 , wherein less than about 5% by weight of the absorbent polymer material has a particle size of 5 μm. 
     
     
       10. The method of  claim 8 , wherein less than about 5% by weight of the absorbent polymer material has a particle size of more than about 1200 μm. 
     
     
       11. The method of  claim 1 , wherein the desired pattern of the perforations extends along a circumferential- and width-wise direction of the endless rotating drum; and wherein the perforations perforate the endless rotating drum in a radial direction thereof, from an inner surface to an outer surface of the endless rotating drum. 
     
     
       12. The method of  claim 11 , wherein each perforation is formed with a converging funnel structure in an inlet region thereof. 
     
     
       13. The method of  claim 1 , wherein an adhesive is applied on the carrier layer prior to the directing of the pulsed particulate material stream through the clustering means onto carrier deposit zones of the carrier layer. 
     
     
       14. The method of  claim 1 , wherein the auxiliary layer is bound or joined to the carrier layer in one or more inter-deposit zones between the carrier deposit zones, via attachment means in the form of grids, patterns, lines and/or dots. 
     
     
       15. The method of  claim 14 , wherein the attachment means are realized using at least one of the following: ultra sonic and/or other thermal, mechanical or thermo-mechanical bonding techniques. 
     
     
       16. The method of  claim 14 , wherein the attachment means are constructed to provide any one of the following: adhesive bonds, thermal bonds, sonic bonds, stapling, stitching; and wherein the attachment means are configured to provide operable pockets of particulate material clusters between the carrier layer and auxiliary layer. 
     
     
       17. The method of  claim 14 , wherein the attachment means are configured to create substantially permanent primary attachments and substantially detachable or temporary secondary attachments, wherein a strength of the secondary attachments is less than a separating force imparted by swelling of the absorbent polymer material when the absorbent polymer material is exposed to liquids. 
     
     
       18. A method for producing a composite structure comprising absorbent particulate material; wherein the method comprises the steps of:
 providing an endless rotating drum incorporating a clustering means with perforations corresponding to a desired pattern; 
 driving the clustering means in a same direction as and in close proximity to a moving carrier layer; 
 feeding a pulsed particulate material stream from a particulate material supply means to the clustering means by creating constantly and quickly repeating pulses of particulate material suspended in airflows acting as a conveyer means; said pulsed particulate material stream comprising absorbent polymer material; 
 directing the pulsed particulate material stream through the clustering means onto carrier deposit zones of the carrier layer; 
 placing an auxiliary layer on top of the carrier layer on which particulate material has been deposited so as to form a sandwich structure; 
 wherein at least one of the carrier layer and the auxiliary layer is made of a hydrophilic non-woven; 
 wherein the auxiliary layer is bound or joined to the carrier layer in one or more inter-deposit zones between the carrier deposit zones, via attachment means in the form of grids, patterns, lines and/or dots. 
 
     
     
       19. The method of  claim 18 , wherein the attachment means are constructed to provide any one of the following: adhesive bonds, thermal bonds, sonic bonds, stapling, stitching; and wherein the attachment means are configured to provide operable pockets of particulate material clusters between the carrier layer and auxiliary layer. 
     
     
       20. The method of  claim 18 , wherein the attachment means are configured to create substantially permanent primary attachments and substantially detachable or temporary secondary attachments, wherein a strength of the secondary attachments is less than a separating force imparted by swelling of the absorbent polymer material when the absorbent polymer material is exposed to liquids. 
     
     
       21. A method for producing a composite structure comprising absorbent particulate material; wherein the method comprises the steps of:
 providing an endless rotating drum incorporating a clustering means with perforations corresponding to a desired pattern; 
 driving the clustering means in a same direction as and in close proximity to a moving carrier layer; 
 feeding a pulsed particulate material stream from a particulate material supply means to the clustering means; said pulsed particulate material stream comprising absorbent polymer material suspended in airflows; 
 directing the pulsed particulate material stream through the clustering means onto carrier deposit zones of the carrier layer; 
 placing an auxiliary layer on top of the carrier layer on which particulate materials has been deposited so as to form a sandwich structure; 
 wherein the desired pattern of the perforations extends along a circumferential- and width-wise direction of the endless rotating drum; and wherein the perforations perforate the endless rotating drum in a radial direction thereof, from an inner surface to an outer surface of the endless rotating drum; and wherein each perforation is formed with a converging funnel structure in an inlet region thereof. 
 
     
     
       22. The method of  claim 21 , wherein the method comprises immobilising, joining and/or restraining the particulate material to at least one of the carrier layer and auxiliary layer.